Item Selection and Content Validity of the Risk Factors of Post-Intubation Tracheal Stenosis Observation Questionnaire for ICU-Admitted Patients.

BACKGROUND
Laryngotracheal stenosis as a late complication of prolonged endotracheal intubation is a life-threatening event. In order to determine the related risk factors for this complication, which may vary among different countries, designing a valid questionnaire is necessary. The aim of this study was to select the items and evaluate the face and content validities of a questionnaire developed for assessment of risk factors of post-intubation tracheal stenosis (PITS) in patients admitted in the intensive care unit.


MATERIALS AND METHODS
A mixed method study design was used in four steps in 2015, i.e., 1) a literature review, 2) focus groups with five experts in the field, 3) consultations with intensive care unit (ICU) specialists and thoracic surgeons, and 4) evaluation of content and face validity with 15 experts in a scientific panel using two self-administered questionnaires. Content validity index (CVI) was computed for individual items as well as the overall scale.


RESULTS
We extracted the items from different sources of information. An initial version of the 52-item questionnaire was developed and classified into four domains including patient characteristics, intubation features, equipment-drugs, and complications. The items with an excellent modified kappa were included in the questionnaire. Five questions received more criticism instead of support and were removed (Item-CVI<0.55, fair modified kappa). The ones with an Item-CVI > 0.60 and a good modified kappa were revised, merged, or retained. The new 43-item questionnaire found a scale-level CVI, averaging (Scale-CVI/Ave) of 0.91.


CONCLUSION
The PITS risk factors questionnaire was developed and validated through item selection, expert opinions, and content validity index.


INTRODUCTION
Endotracheal intubation is performed in patients who require mechanical ventilation. Tracheal stenosis, one of trauma subsequent to a forceful intubation of critically injured patients by less experienced medical staff.
The incidence rate of PITS varies from country to country due to various reasons, like the varying prevalence of the etiological factors, expertise of pre-hospital emergency medical staff, number of ICUs, the experience of ICU staff with non-traumatic intubation, and the quality of the equipment. It was estimated to be 4.6% in the United Kingdom, and 20% in India (1,3). In a prospective study by Stauffer et al., it was reported to be 19 % (4).
There are numerous potential risk factors contributing to PITS, such as cuff pressure, size of the tube in proportion to the tracheal lumen, irritation from cuff materials, age, sex, and bacterial infection (5,6).
Other risk factors may include improper placement of the endotracheal tube, long duration of intubation, the severity of respiratory failure, and insufficient training of the ICU staff for handling endotracheal tubes (7,8). Volpi et al. indicated that some underlying diseases like diabetes mellitus, congestive heart failure, stroke, and tuberculosis can enhance the probability of laryngeal injury (9).
Although most researchers consider cuff pressure to be the main cause of tracheal stenosis (10), it may occur despite using tubes with high volume-low pressure cuffs (10).
The literature shows that 10% of the patients with PITS may remain undiagnosed for over 10 years, or even be wrongly treated for asthma (11). In a patient with a history of intubation for over 24 hours and clinical manifestations of airway obstruction (dyspnea, cough, stridor, wheezing), PITS should be considered as a differential diagnosis (12,13). The natural history of tracheal stenosis can be modified by early diagnosis (1). To best of our knowledge, there is no screening program for those patients who are discharged from ICUs after prolonged intubation. Rigid bronchoscopy and dilatation of the stenosis is the best initial management and could be repeated several times as required. However, the frequent hospital admissions and general anesthesia lead to a significant physical, psychological, and economic surcharge on both, the patients and the health system. Ultimately, in most cases, tracheal resection and reconstruction would be required for optimal treatment (14).
In Iran, traffic accidents constitute one of the most fatal injuries. These occur commonly among the young population (15). Our database for all patients with tracheal diseases (Alborz database), which includes more than 2300 patients in the previous two decades ( [16][17][18][19][20][21], shows that traffic accidents are the main cause of hospitalization and intubation in most of our patients. Previous study estimated a 65% increase in traffic injuries in developing countries in the next 20 years (22). Therefore, it can be inferred that the incidence rate of PITS

Study design
A mixed method study design was chosen to develop a questionnaire for assessment of the risk factors of PITS at the Tracheal Diseases Research Center in 2015.

Literature review
A review of the literature was performed to find any validated instrument for tracheal stenosis. PubMed, Google Scholar, Scientific Information Database (SID), and Cochrane databases were searched without limiting the dates of publication by two experts during 2012 and updated in 2015. Articles in the English and Persian languages were selected. The keywords used to identify the reported risk factors for PITS were "tracheal stenosis/stricture/lesion", "laryngotracheal stenosis/ stricture/lesion", "risk factors, ", "epidemiology" "predisposing factors", "intubation," and "airway". The reference lists in the relevant articles were also used. We did not find any validated questionnaire regarding the risk factors of PITS in the literature. Therefore, the review authors extracted all the related risk factors studied or mentioned in the articles. Some of those risk factors are shown in Table 1 In order to exclude any difficulty or ambiguity, intensivists who had been working in intensive care units for at least three years and thoracic surgeons involved in the management of tracheal stenosis for more than 10 years were invited to participate in a scientific committee. All the selected questions were expressed and discussed by the main investigators. For the face validity, the experts reassessed each question to eliminate any probable obstacles regarding the physicians' feedback. The questionnaire including 52 questions was developed and then confirmed in four domains.

Questionnaire guide
A questionnaire guide was provided for better clarification and comprehensibility of the questions as well as for defining the variables for the respondents. It was uploaded to the website of the research center.

Evaluation of content validity:
We chose the content validity index (CVI) to ensure adequate ability of the items in each thematic domain to precisely measure the PITS risk factors.

Ethical consideration:
The ethics committee of the National Research Institute of Tuberculosis and Lung Diseases (NRITLD) approved the current study.

Statistical analysis:
To analyze the data collected from focused group sessions, the six-step technique of "theme analysis" was In the second round, the S-CVI/Ave was used for consensus estimates of the scale. CVI higher than 0.9 was considered satisfactory for S-CVI/Ave as the average of I-CVIs (33).
To carry out the quantitative evaluation of face validity, the impact score of each item was computed based on the frequency (%) × importance. Scores higher than 1.5 were considered appropriate (34).
Chronbach's alpha coefficient was used for assessing the internal consistency of each domain of the questionnaire. An alpha value equal to or greater than 0.70 was considered acceptable (34).

Qualitative consultations
We  were also rearranged and changed to the "ICU stay" and the "hospital stay." After reviewing and scaling the revised questionnaire by the panelists, S-CVI/Ave of the new 43item questionnaire improved to 0.91 in the second round.
Regarding the face validity, the average impact score was 4.00 (range: 2.87-5.00). Concerning the reliability, Table   3 shows the computed internal consistency of each domain on the questionnaire (Chronbach's alpha). The final version was a structured and closed-ended questionnaire .   The items that should be removed in order to obtain a valid questionnaire but were kept by our experts for the national study are discussed below.

Temperature
Factors like head and body movements, duration of intubation, suction, cough, and temperature could change the pressure of the endotracheal tubes (39-42). Some studies have shown the positive relationship between the level of core body temperature and changes in tube cuff pressure (43)(44). Therefore, body temperature could be considered as a risk factor for PITS.

Type of intubation
Endotracheal intubation can be performed through the oral or nasal path. Orotracheal intubation is easier, faster, and less painful than nasotracheal intubation (45).
Moreover, in a patient, one larger size tube is used in oral intubation when compared to nasal intubation. In this method of airway management, endotracheal tube is also kinked less than the nasal tube. These two benefits of the orotracheal tube can lead to less airflow resistance.
Consequently, the weaning period might be reduced (45).
As laryngeal complications are seen more with orotracheal intubation, nasal intubation is preferred for prolonged intubation despite some limitations such as sinusitis and local abscesses (46).

Bedsore
Bedsores can develop in patients under critical care due to the use of devices, vasoactive medications, and hemodynamic instability (47). The incidence of these sores ranges from 10% to 41% (48)(49).

Cricoid pressure
Cricoid pressure is used to prevent the regurgitation of gastric contents during anesthesia and facilitate the tracheal intubation with rapid sequence induction (53).